I checked the use of engine number through 1939 and I found only these:
Eifelrennen: Von Brauchitsch, not used in the race
Belgium: Von Brauchitsch: 3rd
France: Caracciola, not used in race (car intended for Von Brauchitsch)
Nürburgring: Lang, not used in race
Nürburgring: Brendel, Retired (crash)
Bremgarten: Von Brauchitsch: 3rd
Bremgarten: Lang, not used in race
Bremgarten: Spare car (both M163 and M154)
Yugoslavia: Lang/Bäumer: Retired
Yugoslavia: Von Brauchitsch: DNS
Argentina 1951: Lang: 2 races: 2nd & 3rd
(3 M154's available and only one M163)
So although this engine is regarded as the ultimate pre-war Mercedes-Benz engine it never won a race. A few 3rd's and a 2nd in 1951, that's all
We shouldn't forget that the M154 engines were extensively developed in 1939, including the use of two-stage supercharging. Full details, as mentioned earlier, are in Karl Ludvigsen's Quicksilver Century.
Karl also mentions that the steering fixing was modified, largely at Caracciola's request, to make removal easier. This is especially poignant in view of the difficulty getting Seaman out of the car at Spa.